Abstract: An amount of air taken into an air leading type two-stroke engine is increased to enhance an engine output, and gas emission characteristic deterioration caused by blow-back is inhibited. An inhibition member 16 is disposed between a choke valve 4 in a full open position and a throttle valve 6 in a full open position. The inhibition member 16 includes, for example, a mesh member like a metal mesh. Mixed fuel containing oil is supplied to the air-fuel mixture channel 14. Numerous pores of the inhibition member 16 (mesh member) are occluded by a membrane of oil components of the mixed fuel. Consequently, entry of a blow-back flow of an air-fuel mixture from the air-fuel mixture channel 14 into the air channel 12 through the numerous pores of the flow inhibition member 16 (mesh member) can be inhibited.

Abstract: A suction tube unit connected between a cylinder block and a carburetor in a stratified scavenging engine has a suction tube for mixture made of an elastic material; and a suction tube for stratified scavenging air made of an elastic material. The suction tube for mixture and the suction tube for air have, at respective inlet ends connected to the carburetor, respective wall portions which face each other and have complementary shapes. A clearance space is provided between the wall portions of the suction tube for mixture and the suction tube for air.

Abstract: To enhance responsivity of temperature sensor detecting an engine temperature. A temperature sensor component 40 includes a metal washer 42. The temperature sensor component 40 transfers the engine temperature to a sensor body 46 via the heat transfer washer 42. A cylinder portion 8 of a cylinder block 64 has two bosses 30. The washer 42 of the temperature sensor component 40 is fixed to the boss 30 together with the electronic control unit 20.

Abstract: An engine-driven working machine includes a controller, which varies a control value of a solenoid valve so as to decrease or increase an opening degree of the solenoid valve when a rotating speed of an engine is within a predetermined high rotating speed range and the rotating speed of the engine is lower or higher than a predetermined rotating speed, respectively. In case the controller determines that the engine-driven working machine gets started saw cutting, the controller stops varying the control value of the solenoid valve when the rotating speed of the engine is within the predetermined high rotating speed range and lower than the target rotating speed.

Abstract: The certainty of supplying air to a scavenging channel through a piston groove is improved. In a cylinder wall 2, a gas venting port 10 is formed below and adjacent to a scavenging port 6a. The gas venting port 10 is independent from the scavenging port 6a, and is opened/closed by a piston as each of an air port 4a and the scavenging port 6a is. Upon a piston groove 8 being brought into communication with the gas venting port 10 as a result of the piston moving up (FIG. 1(II)), blown-back gas in a piston groove 8 can move to a crankcase through the gas venting port 10. Along with this, air can enter the piston groove 8 from the air port 4a.

Abstract: A chainsaw includes a chainsaw body, a guide bar and a saw chain. The chainsaw body includes an oil tank, an oil pump to supply oil stored in the oil tank to a sliding portion between the guide bar and the saw chain, a first extension chamber arranged above the oil tank and a second extension chamber arranged above the first extension chamber. The oil tank communicates with the first extension chamber via a first flow path, the first extension chamber communicates with the second extension chamber via a second flow path and a vent hole communicating with the outer space is formed in the second extension chamber.

Abstract: The present invention is to prevent mixing of fresh air and an air-fuel mixture when a throttle valve is fully opened and increase a delivery ratio. A main nozzle (30) is surrounded by a tunnel-like air flow guiding member (52). The air flow guiding member (52) is opened at its front and back sides. A whole amount of fuel discharged via a main nozzle (30) is sent to a downstream side by an air flow created by the air flow guiding member (52). When a throttle valve (22) and a choke valve (24) are both in a fully-opened state, fresh air flows into an air-fuel mixture passage (12) through a gap between these valves (22, 24).

Abstract: A cyclone separator having a circular cross section is arranged upstream of an air filter. An introduction passage extends from a branch air inlet, which is provided at a position displaced from a main passage, to the cyclone separator. A margin space where at least part of air introduced in the introduction passage flows is formed in the introduction passage before the cyclone separator. A swirl flow occurring in the cyclone separator starts at this margin space.

Abstract: To enhance responsivity of temperature sensor detecting an engine temperature. A temperature sensor component 40 includes a metal washer 42. The temperature sensor component 40 transfers the engine temperature to a sensor body 46 via the heat transfer washer 42. A cylinder portion 8 of a cylinder block 64 has two bosses 30. The washer 42 of the temperature sensor component 40 is fixed to the boss 30 together with the electronic control unit 20.

Abstract: A handle includes: a switch lever having an operational portion in an inverted U-shape, and configured to press an on/off switch when the operational portion is gripped and pressed; a handle body provided with the on/off switch mounted thereto and having an inner peripheral slit from which the operational portion of the switch lever housed in the handle body projects; a spring having a supported portion and a pair of arms extending from the supported portion, housed in the handle body, and biasing and pushing the switch lever back; and a plurality of limiters provided at locations in either the handle body or the switch lever at a distance from the spring, and configured to limit movement of the switch lever.

Abstract: An engine-driven brush cutter (100) equipped with a safety device (42) that includes an acceleration sensor unit (24) attached to a drive unit (4) in an aslant orientation such that a detection axis (DA) of the sensor unit (24) inclines by an angle (?1) relative to the up-and-down direction (V) of the brush cutter (100). This inclined orientation of the detection axis (DA) contributes to lowering the sensitivity of the sensor unit (24) to engine vibration to which the safety device should not be sensitive so much.

Abstract: An engine-driven brush cutter (100) equipped with a safety device (42) that includes an acceleration sensor unit (24) attached to a drive unit (4) in an aslant orientation such that a detection axis (DA) of the sensor unit (24) inclines by an angle (?1) relative to the right-and-left direction (R-L) of the brush cutter (100). This inclined orientation of the detection axis (DA) contributes to lowering the sensitivity of the sensor unit (24) to impulses in the direction parallel to a moving direction of a cutting blade (40) operated by an operator at work.

Abstract: A reciprocating working machine has a lower blade and an upper blade overlapping each other. The lower and upper blades have respective elongated apertures slidably fit around lower and upper eccentric cams, respectively. The lower and upper eccentric cams are arranged at a 180-degree phase from each other. One of the upper eccentric cam and the lower blade has a beveled surface facing the other. The lower blade and the upper eccentric cam are relatively moved away from each other via the beveled surface.

Abstract: Provided is a battery-powered working machine including a protective bracket which is able to be secured to a casing while being in engagement with a battery pack, which is capable of preventing theft of the battery pack, and which separates a casing-side connection terminal from a battery-side connection terminal at a distance to keep the casing-side and battery-side connection terminals and out of contact with each other.

Abstract: To balance a “low-temperature scavenging effect” and a “high-temperature scavenging effect.” A scavenging system applicable to a leading-air type two-stroke air-cooled engine has a low-temperature scavenging passage and a high-temperature scavenging passage. The low-temperature scavenging passage has first and second passages and includes scavenging ports at upper end parts thereof. The high-temperature scavenging passage has first and second passages and includes scavenging ports at upper end parts thereof. An air is filled through a piston groove into the passages. The low-temperature scavenging passage has a relatively small capacity. The high-temperature scavenging passage has a relatively large capacity.

Abstract: To allow an intake negative pressure to directly act on a fuel outlet formed on a nozzle tube, and to guide a fuel discharged from the fuel outlet in the nozzle tube to the fuel-air mixture passage. A rotary carburetor (200) has a guide plate member (42) downstream of a fuel outlet (30) located in a through-hole (14). The guide plate member (42) has both side edges (42b) away from an inner wall surface (14a) of the through-hole (14). The through-hole (14) is divided by the guide plate member (42) into a first passage portion (44) and a second passage portion (46). The first passage portion (44) communicates through a piston groove with a scavenging passage of a cylinder. The fuel discharged from the fuel outlet (30) is guided by the guide plate member (42) to the second passage portion (46) and is supplied through the second passage portion (46) to a fuel-air mixture passage (24) of an engine intake system.

Abstract: To satisfy both a request for ensuring worker's safety at the engine start and a worker's request for promptly starting a work, on the premise of a working machine including an engine RPM suppression mode. A working machine (1) has a centrifugal clutch (6). The engine RPM suppression mode is executed at the start of an internal combustion engine (2). With the RPM suppression mode, the RPM of the internal combustion engine (2) is controlled not to exceed a clutch-in RPM. The working machine (1) has a mode cancelling means (S5) canceling the engine RPM suppression mode when a predetermined mode cancelation condition for cancelling the engine RPM suppression mode is satisfied, and a cancellation condition changing means (S2) changing the mode cancelation condition depending on a change in an engine operational state and/or an environment.

Abstract: The intake structure for an internal combustion engine includes: a collision surface configured to face an inlet of a carburetor; a deflecting surface configured to deflect a blowback flow, which is to diffuse after colliding against the collision surface, in one direction along the collision surface; a receiving surface configured to receive the blowback flow deflected by the deflecting surface; and a fuel-accumulating surface formed below the collision surface. A first clearance between an air-guiding direction distal end of the deflecting surface and the receiving surface is brought into communication to a downstream side of a filter of an air cleaner in a fresh-air intake direction so as to act as a main intake passage for fresh air.

Abstract: A rotary-type carburetor (1) according to the present invention includes a body (4) having a bore (2) with a circular cross section, and a valve element (6) to be contained in the bore (2). The valve element (6) rotates between a closed position where the valve passage (16) is blocked from communicating with the body passages (10a, 10b), and a fully-opened position where the valve passage (16) and the body passages (10a, 10b) are aligned. When the valve element (6) is located in an idle position, an air flowing through the body passages (10a, 10b) and the valve passage (16) is prevented from being flown into the bore end part (12). When the valve element (6) is located in a fully-opened position, a portion of the air flowing from an upstream part (10a) of the body passage is bypassed into the upstream communication part (32).